Located within the special flood hazard areas established in § 153.07 of this chapter, where streams exist, but no base flood data has been provided and where a floodway has not been delineated, the following provisions shall apply.
   (A)   The Administrator shall obtain, review and reasonably utilize any base flood elevation and floodway data available from any federal, state or other sources, including data developed as a result of these regulations (see division (B) below), as criteria for requiring that new construction, substantial improvements or other development in approximate A Zones meet the requirements of §§ 153.40 and 153.41 of this chapter.
   (B)   Require that all new subdivision proposals and other proposed developments (including proposals for manufactured home parks and subdivisions) greater than 50 lots or five acres, whichever is the lesser, include within such proposals base flood elevation data.
   (C)   Within approximate A Zones, where base flood elevations have not been established and where such data is not available from other sources, require the lowest floor of a building to be elevated or floodproofed to a level of at least three feet above the highest adjacent grade (as defined in § 153.05 of this chapter). All applicable data including elevations or floodproofing certifications shall be recorded as set forth in § 153.26 of this chapter. Openings sufficient to facilitate automatic equalization of hydrostatic flood forces on exterior walls shall be provided in accordance with the standards of § 153.41 of this chapter.
   (D)   Within approximate A Zones, where base flood elevations have not been established and where such data is not available from other sources, no encroachments, including structures or fill material, shall be located within an area equal to the width of the stream or 20 feet, whichever is greater, measured from the top of the stream bank, unless certification by a state registered professional engineer is provided demonstrating that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the city. The engineering certification should be supported by technical data that conforms to standard hydraulic engineering principles.
   (E)   New construction and substantial improvements of buildings, where permitted, shall comply with all applicable flood hazard reduction provisions of §§ 153.40 and 153.41 of this chapter. Within approximate A Zones, require that those divisions of § 153.41 of this chapter dealing with the alteration or relocation of a watercourse, assuring watercourse carrying capacities are maintained and manufactured homes provisions are complied with as required.
(Ord. 703, passed 5-24-2010)